The present application relates to a semiconductor device having an oxide semiconductor film, to a display unit, and to an electronic apparatus.
An oxide containing elements such as zinc (Zn) and indium (In) exerts an excellent property as an active layer of a semiconductor device, and is recently being developed for applications to TFT, a light-emitting device, and a transparent conductive film. In particular, it has been known that an electron mobility of TFT using a composite oxide containing elements such as Zn, In, and Ga is large as compared to that of the TFT using amorphous silicon (a-Si:H) generally used for a liquid crystal display, and an excellent electrical characteristic is exerted.
In the TFT (Thin Film Transistor) using such an oxide semiconductor, a bottom-gate type TFT and a top-gate type TFT have been reported up to now. The bottom-gate type TFT has a configuration in which a thin-film layer of the oxide semiconductor is provided on a gate electrode with a gate insulating film provided therebetween. This structure is similar a structure of the TFT, which is commercialized at the present, in which amorphous silicon is used for a channel. Therefore, it is possible to divert an existing manufacturing process of the TFT using amorphous silicon thereto easily, and the bottom-gate type structure is often used in the TFT using an oxide semiconductor.
As described above, an oxide semiconductor material is used as a channel film of the TFT. On the other hand, a method for improving electrical conductivity of the oxide semiconductor material and applying it to an electrode of a capacitor has also been studied (for example, see Japanese Unexamined Patent Application Publication No. 2011-100091). In the oxide semiconductor material, carriers are generated due to oxygen defects. That is, a reduction process is applied to the oxide semiconductor material, and thereby it is possible to improve electrical conductivity thereof. Examples of the reduction process include an argon process, an annealing process under a nitrogen (N2) atmosphere, and a hydrogen process (for example, see Japanese Unexamined Patent Application Publication Nos. 2010-166030, 2010-222214, and 2011-091279). The hydrogen process may be, for example, hydrogen plasma irradiation.